Diode-pumped miniaturized lasers operating in the green region of the optical spectrum are desirable for many applications such as printing, optical data storage, underwater communication, and medical instrumentation. The term miniaturized laser is generally understood in the art to mean a monolithic solid-state laser having mirrors directly deposited on opposite facets of a gain medium. Of particular interest is a diode-pumped, miniaturized, frequency-doubled green laser. The output radiation of a green laser is essentially free of large-amplitude fluctuations, an operating characteristic which makes the green laser especially attractive for use in optical data storage. Additionally, a miniaturized UV laser can be fabricated by the emplacement of a frequency-doubling, non-linear crystal at the output of a miniaturized green laser to obtain the second harmonic of green light, which corresponds to radiation of UV wavelength.
However, such applications remain largely unrealized because of the practical difficulties encountered in fabricating a miniaturized green laser. These difficulties can be explained by describing some of the conventional laser configurations used for the generation of green laser light.